This is part of the the work towards issue #437

This is part of the work towards issue #437

This is part of the work towards issue #437

Phil/437 workspaces tutorial

Closes #437

See merge request !519

Element paths should always be completed from the root element folder
defined by the element-path key in project.conf. Fix complete_path() to
always search into its given base_directory argument.

See issue #448